The major goal of this proposal is to characterize vasomotor function in SOD2+/-mice. Studies are planned in the aortae and carotid arteries of wild-type control and SOD2+/- mice because diseases such as hypertension and atherosclerosis, which affect these vessels, are risk factors for stroke and are associated with elevated levels of reactive oxygen species in the vascular wall. Under normal conditions, and after experimentally inducing oxidant stress using menadione in vitro and lipopolysaccharide in vivo, vessels from both wild-type control and SOD2+/-mice will be studied to determine vascular responses to acetylcholine and papaverine. In some experiments, SOD1&3 will be inhibited using DETCA to further unmask the function of SOD2. The superoxide dependency of any observed vascular dysfunction will be determined by using tiron to scavenge superoxide. In addition, the levels and location of superoxide and other reactive oxygen species will be determined in vessels from both wild-type control and SOD2+I-mice under normal conditions and after experimentally inducing oxidant stress. Levels of superoxide will be measured using lucigenin chemiluminescence and superoxide will be localized using hydroethidine staining. The location and relative levels of other reactive oxygen species (ROS) will be estimated using dichlorofluorescin (DCF) fluorescence.